What does HMRC mean when they say your client’s behaviour has been deliberate and concealed?

The level of HMRC tax geared penalty will depend upon a taxpayer’s behaviour that brought about that loss of tax in the first place. But, how do you establish a taxpayers behaviour?
What is a “formal information request” from HMRC?

Knowing whether a request from HMRC is a formal information request or an informal request should impact how a taxpayer deals with the request and the outcome.